On 02/07/2015 15:58, Laurent Vivier wrote: > Since any /dev entry can be treated as a raw disk image, it is worth > noting which devices can be accessed when and how. /dev/rdisk nodes are > character-special devices, but are "raw" in the BSD sense and force > block-aligned I/O. They are closer to the physical disk than the buffer > cache. /dev/disk nodes, on the other hand, are buffered block-special > devices and are used primarily by the kernel's filesystem code.
So the right thing to do would not be just to set need_alignment, but to probe it like we do on Linux for BDRV_O_NO_CACHE. I'm okay with doing the simple thing, but it needs a comment for non-BSDers. Paolo